Calcium channel blockers. Is it time to split the lump?

Nifedipine Exacerbates Lipogenesis in the Kidney via KIM-1, CD36, and SREBP Upregulation: Implications from an Animal Model for Human Study

Dysregulation of fatty acid oxidation and accumulation of fatty acids can cause kidney injury. Nifedipine modulates lipogenesis-related transcriptional factor SREBP-1/2 in proximal tubular cells by inhibiting the Adenosine 5‘-monophosphate (AMP)-activated protein kinase (AMPK) pathway in vitro. However, the mechanisms by which nifedipine (NF) modulates lipotoxicity in vivo are unclear. Here, we examined the effect of NF in a doxorubicin (DR)-induced kidney injury rat model. Twenty-four Sprague–Dawley rats were divided into control, DR, DR+NF, and high-fat diet (HFD) groups. The DR, DR+NF, and HFD groups showed hypertension and proteinuria. Western blotting and immunohistochemical analysis showed that NF significantly induced TNF-α, CD36, SREBP-1/2, and acetyl-CoA carboxylase expression and renal fibrosis, and reduced fatty acid synthase and AMPK compared to other groups (p < 0.05). Additionally, 18 patients with chronic kidney disease (CKD) who received renal transplants were enrolled to examine their graft fibrosis and lipid contents via transient elastography. Low-density lipoprotein levels in patients with CKD strongly correlated with lipid contents and fibrosis in grafted kidneys (p < 0.05). Thus, NF may initiate lipogenesis through the SREBP-1/2/AMPK pathway and lipid uptake by CD36 upregulation and aggravate renal fibrosis in vivo. Higher low-density lipoprotein levels may correlate with renal fibrosis and lipid accumulation in grafted kidneys of patients with CKD.

An Investigative Review for Pharmaceutical Analysis of 1,4-Dihydropyridine-3,5-Dicarboxylic Acid Derivative: Cilnidipine

Hypertension is commonly a quiet condition, and it expands the risk of heart diseases and stroke. Calcium delivers a substantial role in cardiovascular functions and hence is essential for cardiac automaticity and functioning. Calcium channel antagonists are the choice of drugs for the management of cardiovascular diseases; they precisely stop the introduction of calcium through L-type calcium channels are existing channels in the heart. Cilnidipine belongs to the class 4th generation calcium channel blockers as a foremost therapeutic agent used in the treatment of hypertension and heart diseases. This review article focuses on an inclusive account of crucial analytical methodologies used for the pharmaceutical analysis of cilnidipine in pure forms, biological samples and pharmaceuticals. According to literature reports several analytical techniques such as hyphenated techniques, high-performance thin-layer chromatography, high-performance liquid-chromatography, capillary electrophoresis, voltammetry, UV/Vis-spectrophotometry, and Fourier-transform infrared spectroscopy approaches have been used for determination of cilnidipine alone or in the combined dosage form. We have also discussed the pharmacopeial assay methods, physicochemical properties, and also depict the stacked column chart for year wise publication count for cilnidipine. From literature, concluded that the high-performance liquid-chromatography and UV/Vis-spectrophotometry methods are the most prevailing methods for the analysis of cilnidipine. The data presented in this review may provide a very significant base for further studies on cilnidipine in the area of drug analysis.

Are prostaglandins or calcium channel blockers efficient for free flap salvage? A review of the literature

The free flap failure rate is less than 5%. The responsible mechanisms of postoperative secondary ischemia are mostly vascular. The main postoperative complication leading to flap failure is thrombosis. Different strategies have been reported to improve the reliability of flaps and decrease the risk of partial or total necrosis: thus, pharmacologic agents have been studied to reduce the risk of microvascular thrombosis. The aim of this review was to evaluate the effect of calcium channel blockers and prostaglandins on free skin flap survival. A systematic review of the literature was performed to identify articles studying the efficacy of calcium channel blockers and prostaglandins on free flap survival. After full text reading, eleven articles were finally included. Eight articles investigated the role of prostaglandins in free tissue transfers, two in rats subjects, one in rabbits, five in humans. Two articles studied the effect of calcium channel blockers on free flaps, one in rats subjects, one in rabbits. One article studied in different groups the effect of calcium channel blockers and prostaglandins on free flaps in rabbits. Literature regarding the efficacy of calcium channel blockers and prostaglandins to salvage free flap is poor and mainly based on animal models. Nevertheless, studies on prostaglandins showed a slight efficiency of these molecules for free flap salvage. Results are less reliable for calcium channel blockers and dependent on the molecule used. In conclusion, there is a lack of evidence to use them in clinical practice.

Effects of calcium channel blockers comparing to angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in patients with hypertension and chronic kidney disease stage 3 to 5 and dialysis: A systematic review and meta-analysis

Background

Calcium channel blocker (CCB) or two renin angiotensin aldosterone system blockades (RAAS), angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), are major potent and prevalently used as initial antihypertensive agents for mild to moderate hypertension, but no uniform agreement as to which antihypertensive drugs should be given for initial therapy, especially among chronic kidney disease (CKD) patients.

Design

A systematic review and meta-analysis comparing CCBs and the two RAAS blockades for hypertensive patients with CKD stage 3 to 5D. The inclusion criteria for this systematic review was RCT that compared the effects of CCBs and the two RAAS blockades in patients with hypertension and CKD. The exclusion criteria were (1) renal transplantation, (2) CKD stage 1 or 2, (3) combined therapy (data cannot be extracted separately). Outcomes were blood pressure change, mortality, heart failure, stroke or cerebrovascular events, and renal outcomes.

Results

21 randomized controlled trials randomized 9,492 patients with hypertensive and CKD into CCBs and the two RAAS blockades treatments. The evidence showed no significant differences in blood presser change, mortality, heart failure, stroke or cerebrovascular events, and renal outcomes between CCBs group and the two RAAS blockades group. The publication bias of pooled mean blood presser change that was detected by Egger’s test was non-significant.

Conclusions

CCBs has similar effects on long term blood pressure, mortality, heart failure, stroke or cerebrovascular events, and renal function to RAAS blockades in patients CKD stage 3 to 5D and hypertension.

Resting heart rate, heart rate reserve, and metabolic syndrome in professional firefighters: A cross-sectional study

BACKGROUND

Little is known about the associations of resting heart rate (RHR) and heart rate reserve (HRR) with metabolic syndrome (MetS) in firefighters.

METHODS

For each of 288 professional firefighters, HRR was calculated as the difference between measured RHR and estimated maximum HR. For comparison, VO₂ max based on a treadmill test was included. MetS was defined according to the NCEP/ATP III criteria.

RESULTS

The prevalence of MetS was 14.2%. The average of RHR was 61.5 beat/min. Only 5.8% of the firefighters had RHR of ≥80 beat/min. Between the firefighters in the lowest and highest quintiles, the prevalence ratios (95% confidence intervals) for MetS were 1.88 (0.71-4.94), 5.90 (1.74-20.02), and 8.03 (1.86-34.75) for RHR, HRR, and VO₂ max, respectively. Both HRR and VO₂ max, but not RHR, were significantly associated with MetS and its most component risk factors in middle-aged firefighters.

CONCLUSIONS

HRR, a simple cardiovascular fitness measure, was inversely associated with MetS among middle-aged professional firefighters.

Efficacy and safety of dual calcium channel blockade for the treatment of hypertension: a meta-analysis

BACKGROUND

Dual calcium-channel blocker (CCB) with a dihydropyridine (DHP) and a nondihydropyridine (NDHP) has been proposed for hypertension treatment. However, the safety and efficacy of this approach is not well known.

METHODS

A MEDLINE/EMBASE/CENTRAL search for randomized clinical trials published on this topic from 1966 to February 2012 was performed. Efficacy outcomes of decrease in systolic (SBP) and diastolic (DBP) blood pressures from baseline, changes in heart rate (HR), and adverse effects were compared between dual CCB therapy vs. DHP or NDHP. SBP, DBP, and HR were expressed as weighted mean deviation (WMD).

RESULTS

A total of 6 studies with 153 patients were included. Dual CCB produced a significantly greater reduction in SBP (21.6±9.2 mmHg) from baseline than DHP (10.3±6.3 mmHg (WMD = 10.9 mmHg, P < 0.0001)) or NDHP (8.9±4.2 mmHg (WMD = 14.1 mmHg, P = 0.002)). Dual CCB therapy reduced DBP from baseline more than either monotherapy (dual CCB = 17.5±10.2 mmHg vs. DHP = 11.6±8.7 mmHg, WMD = 5.5 mmHg, P < 0.001; and NDHP = 10.5±5.6 mmHg, WMD = 5.3 mmHg, P = 0.03). Dual CCB therapy had significantly lower HR compared to DHP (P < 0.001) but was comparable to NDHP (P = 0.12) (Delta change dual CCB = -4.0±3.5 vs. DHP = -2.0±1.5 and NDHP = -6.0±5.0 beats/min). Dual CCB therapy did not increase adverse effects.

CONCLUSIONS

Dual CCB therapy lowers blood pressure significantly better than CCB monotherapy, without an increase in adverse events. However, given the lack of long-term outcome data on efficacy and safety, dual CCB therapy should be used with restraint, if at all. Large-scale long-term trials are needed to further evaluate such a strategy.

Calcium channel blockers

KEY POINTS AND PRACTICAL RECOMMENDATIONS: •  Calcium channel blockers, which dilate arteries by reducing calcium flux into cells, effectively lower blood pressure, especially in combination with other drugs, and some formulations of agents of this class are approved for treating angina or cardiac dysrhythmias. •  Calcium channel blockers reduce blood pressure across all patient groups, regardless of sex, race/ethnicity, age, and dietary sodium intake. •  Nondihydropyridine calcium channel blockers are more negatively chronotropic and inotropic than the dihydropyridine subclass, which is important for patients with cardiac dysrhythmias or who need β-blockers. •  Extensive experience in comparative randomized trials indicates that an initial calcium antagonist can prevent all major types of cardiovascular disease, except heart failure (for which a diuretic is superior). Initial dihydropyridine calcium channel blockers have not reduced the rate of progression of renal disease as well as inhibitors of the renin-angiotensin system, although members of the nondihydropyridine subclass can reduce albuminuria. •  High doses of dihydropyridine calcium channel blockers often cause edema, headache, flushing and tachycardia; high doses of verapamil can cause constipation. Diltiazem and verapamil have important drug interaction with digoxin and cyclosporine, among others.

Combination therapy with renin-angiotensin system blockers: Will amlodipine replace hydrochlorothiazide?

Amlodipine is a highly effective and safe antihypertensive dihydropyridine calcium channel blocker. It is even more effective when used in combination with other antihypertensive medications, including hydrochlorothiazide. When antihypertensive calcium channel blockers were first introduced, evidence in the laboratory that they had some natriuretic properties was adduced to suggest that they would be "the diuretics of the 1990s." This turned out not to be the case. Because of its clinical efficacy, amlodipine is frequently used in fixed-dose combination products, but it is not likely to replace hydrochlorothiazide.

Diltiazem to treat sinus tachycardia in critically ill patients: a four-year experience

OBJECTIVES

To determine whether an intravenous infusion of the calcium channel blocker diltiazem was effective and safe in treating sinus tachycardia in critically ill adult patients with contraindications to beta-blockers or in whom beta-blockers were ineffective.

DESIGN

Retrospective chart review.

SETTING

University medical center.

PATIENTS

The records of 171 surgical intensive care unit patients with sinus tachycardia treated with intravenous diltiazem were evaluated.

INTERVENTIONS

In all patients with sinus tachycardia (heart rate >100 beats/min), heart rate control with intravenous diltiazem was attempted after adequate intravascular volume expansion, pain, and anxiety control. In all patients, beta-blockade either was contraindicated or (in 7%) had failed. Intravenous diltiazem was administered as a slow 10-mg bolus dose (0.1-0.2 mg/kg ideal body weight), and then an infusion was started at 5 or 10 mg/hr and increased up to 30 mg/hr, as needed, to decrease heart rate to <100 beats/min. Variables retrospectively collected included demographic data, preinfusion blood pressure, mean arterial pressure, heart rate, and preinfusion pressure-rate quotients (pressure-rate quotient = mean arterial pressure / heart rate). Intravenous bolus dose, when given, and diltiazem infusion rate and time necessary to achieve the target heart rate also were recorded. The lowest heart rate recorded within 24 hrs from the initiation of the infusion and the time necessary to achieve the lowest heart rate after beginning the infusion were recorded.

MEASUREMENTS AND RESULTS

Of 171 patients studied, 97 (56%) were classified as responders. Multiple linear regression suggested that response could be predicted by age, pressure-rate quotients, baseline mean arterial pressure, and central nervous system failure. In the responders, a heart rate <100 beats/min was achieved in an average of 2 hrs, at a mean diltiazem infusion of 13.3 mg/hr. The lowest rate reached by the responders in a 24-hr period averaged 86 beats/min and was achieved in 4.8 hrs with a mean infusion rate of 14.8 mg/hr. Both target and lowest rate values were statistically different from baseline heart rate.

CONCLUSION

Diltiazem was effective in achieving short-term control of heart rate in 56% of the patients, virtually without adverse effects, where beta-blockade was contraindicated or ineffective.

Antihypertensives and myocardial infarction risk: the modifying effect of history of drug use

PURPOSE

Confounding by indication is common in observational studies of outcomes that treatment is intended to affect. In light of the stepped-care approach to hypertension management, we reexamined the controversy around myocardial infarction (MI) risk in relation to antihypertensive agents by considering past drug history both as a confounder and as an effect modifier.

METHODS

Case-control design nested within a cohort of 19,501 adults initiating therapy with angiotensin-converting enzyme inhibitors (ACEI), calcium channel blockers (CCB) or beta-blockers in Saskatchewan (1990-93) and followed up to 1997. MI cases were identified using death certificates and hospital discharge diagnoses (ICD-9,410). Four controls were matched to each case to account for duration and timing of follow-up.

RESULTS

812 MI cases were identified, of which 26% were fatal. At first, current use of CCB and ACEI (versus beta-blockers) appeared to be associated with an increased risk of MI (RR = 2.2; 95% CI = 1.8-2.7 and RR = 1.3; CI = 1.0-1.6 respectively). Adjustment for drug use history attenuated both associations (RR = 1.6; CI = 1.1-2.2 and RR = 1.0; CI = 0.7-1.4). Moreover, the risk for CCB use disappeared when restricted to patients who had already used these agents in the past (RR = 1.1; CI = 0.77-1.7) whereas a high risk of MI for ACEI was found in digoxin users (RR = 9.4; CI = 3.2-27.5).

CONCLUSION

Past drug history can be both a confounder and an effect modifier in observational studies. We found adjustment for medication history to attenuate the associations between antihypertensive agents and MI risk. In addition, the estimates significantly varied across drug history profiles thus suggesting the presence of preferential prescribing of specific drug classes to high-risk patients.

Studies on the cardiovascular depressant effects of N-ethyl- and N-benzyl-1,2-diphenylethanolamines in the rat: elucidation of the mechanisms of action

The influence and mechanisms of action of N-ethyl- and N-benzyl-1,2-diphenylethanolamines (compounds E and B, respectively) on the arterial blood pressure and the heart rate of the rat together with their effects on CaCl2-induced arrhythmias in the rat were investigated. Both E and B in doses of (1.5-12 micromol/kg IV) decreased the arterial blood pressure and the heart rate in a dose-dependent manner. Studies with various receptor blockers, enzyme inhibitors and CaCl2 revealed that E-induced cardiovascular depressant effects were mainly due to CaCl2 channel blocking action and activation of cyclic guanylyl cyclase or release of NO whereas the cardiovascular effects of B seemed to involve both blockade of Ca2+ channels and activation of parasympathetic ganglia. Both compounds (12-14.5 micromol/kg) completely protected the rat against CaCl2 (60 mg kg(-1))-induced tachyarrhythmias. The B compound seemed to be several times more potent than the E compound in its cardiovascular depressant actions. The results suggest the potential usefulness of both compounds in the treatment of hypertension and supraventricular arrhythmias.

Comparison of nifedipine alone and with diltiazem or verapamil in hypertension

Receptor binding studies suggest that combinations of calcium channel blockers may result in either enhanced or diminished pharmacological effects, but clinical data in hypertension are incomplete. In this study, we compared blood pressure reductions using nifedipine alone, nifedipine plus diltiazem, and nifedipine plus verapamil and determined whether combinations alter nifedipine pharmacokinetics. After determination of baseline blood pressures. 16 subjects with essential hypertension (12 men, 4 women; mean age, 48 years) received 30 mg/d open-label, sustained release nifedipine for 2 weeks. If still hypertensive (n = 16), they were randomized (double-blind) to receive either additional sustained release diltiazem or sustained release verapamil, both 180 mg/d, for 2 weeks and were then crossed-over for the final 2 weeks of the study. All medications were once-daily, extended-release formulations. Blood pressures and nifedipine plasma concentrations were measured during the final day of each treatment. Overall, each combination lowered mean systolic and diastolic pressures more than nifedipine alone. Mean supine diastolic pressures were significantly lower at 8 hours (77.6 versus 84.6 mm Hg, P = .001) and 12 hours (81.5 versus 87.1 mm Hg, P = .04) with nifedipine plus diltiazem than nifedipine plus verapamil. Mean nifedipine concentrations were inversely correlated with mean blood pressures. Mean nifedipine area under the curve values were greater with diltiazem than verapamil (1430 versus 1134 ng.h/mL, P = .026), with each greater than nifedipine alone (957 ng.h/mL). Nifedipine plus diltiazem had a greater antihypertensive effect than nifedipine plus verapamil. Diltiazem caused greater increases in nifedipine plasma concentrations than did verapamil. These data suggest that combined calcium channel blockers result in additive antihypertensive effects, perhaps because of a pharmacokinetic interaction.

Long-term survival and use of antihypertensive medications in older persons

OBJECTIVE

To determine whether older persons with hypertension who use specific calcium antagonists and ACE inhibitors have a different risk of mortality than those using beta-blockers.

DESIGN

A prospective cohort study continuing from 1988 through 1992.

SETTING

Three communities of the Established Populations for Epidemiologic Studies of the Elderly.

PARTICIPANTS

Hypertensive participants aged > or = 71 years (n = 906) who had no evidence of congestive heart failure and who were using either beta-blockers (n = 515), verapamil (n = 77), diltiazem (n = 92), nifedipine (n = 74), or ACE inhibitors (n = 148). Nifedipine was of the short acting variety.

MEASUREMENTS

The main outcome measure was all-cause mortality. Age, gender, smoking, HDL-cholesterol, blood pressure, intake of digoxin and diuretics, physical disability, self-perceived health, and comorbid conditions were examined as confounders.

RESULTS

During 3538 person-years of follow-up, 188 participants died (53 deaths per 1000 person-years). Compared with beta-blockers, after adjusting for age, gender, comorbid conditions and other health-related factors, the relative risks (95% confidence interval) for mortality associated with use of verapamil, diltiazem, nifedipine, and ACE inhibitors were 0.8 (0.4-1.4), 1.3 (0.8-2.1), 1.7 (1.1-2.7), and 0.9 (0.6-1.4), respectively. The results were unchanged after excluding participants with other potential contraindications to beta-blockers and after stratifying on coronary heart disease and use of diuretics. Higher doses of nifedipine were associated with higher mortality.

CONCLUSION

Compared with beta-blockers, use of short acting nifedipine was associated with decreased survival in older hypertensive persons. However, selective factors influencing the use of specific drugs in higher risk patients could not be completely discounted, and final conclusions will depend on clinical trials.